The present invention relates to styrene polymers including homopolymers and copolymers having a new stereoregular structure and more particularly to styrene polymers in which the stereoregular structure of side chains relative to the polymer main chain is mainly syndiotactic.
As is well known, styrene homopolymers such as polystyrene and polyparamethylstyrene, and styrene copolymers are generally produced by techniques such as radical polymerization, anionic polymerization, cationic polymerization and polymerization using Ziegler-type catalysts. These styrene polymers are divided into three groups, isotactic, syndiotactic and atactic polymers, depending on the steric configuration of side chains thereof. It has heretofore been known that usual radical, anionic and cationic polymerization methods provide styrene polymers having mainly an atactic structure, and that the polymerization methods using a Ziegler-type catalyst provide styrene polymers having mainly an isotactic structure.
A number of methods of preparing styrene polymers and their structures have been reported. However, preparation of styrene polymers of high syndiotactic structure (excluding such model substances as trimers to pentamers prepared by organic chemical preparation techniques or alternating copolymers wherein styrene is copolymerized with a non-styrene monomer such as methyl methacrylate) has not yet been reported.